Two genetic tools assign all cells as `negative` with testing data

[LuisHeinzlmeier]

*_genetic_overview_assignment.csv

method,count_overall,match_demuxlet,match_freemuxlet,match_souporcell,match_vireo,0,1,doublet,negative
demuxlet,468,468,468,468,468,0,0,0,468
freemuxlet,500,468,500,500,500,122,100,3,275
souporcell,500,468,500,500,500,222,233,5,40
vireo,500,468,500,500,500,0,0,0,500

demuxlet: statgen/popscle#81
vireo: single-cell-genetics/vireo#122